Av data conversion device and method

ABSTRACT

An AV data conversion apparatus has a verification file confirmation means ( 11 ) for reading an AV data file ( 101 ) containing AV data including video information and audio information, and a verification file ( 102 ) for the AV data file, and confirming if the AV data file and verification file mutually correspond; a plurality of stream conversion means ( 13 ) for changing the AV data to a specific format; and a conversion method determining means ( 12 ) for selecting from among the plural stream conversion means at least one stream conversion means for changing the AV data to the specific format based on verification file content.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an AV data conversion apparatus andmethod for converting AV data compressed according to the MPEG standard,for example, to data conforming to the VR format and recording theconverted AV data to an optical disc.

2. Description of Related Art

DVD-RAM and similar optical disc drives record AV data such asMPEG-encoded AV data according to the industry-standard Video Recording(VR) format for recording AV data. Files for storing AV data accordingto the VR format are called “VRO files”, and conform to the MPEGstandard. Some limitations are, however, applied to the MPEG standard inthis case so that disc content can be edited in real time. This meansthat not all MPEG files are interchangeable with VRO files, and dataconversion, including changing the pack size, to conform to the VRformat is needed in order to record an MPEG file that is not compliantwith the VR format.

FIG. 19 is a block diagram of a conventional AV data converter forconverting MPEG or other AV data to VR format data and then recordingthe resulting VR data. The AV data converter shown in FIG. 19 reads anMPEG-format data file 101 that is non-compliant with the VR format,converts the MPEG data file 101 to VR-compliant VRO data file 107 andIFO data file 108, and records the converted files to an optical disc50. To accomplish this, the AV data converter has an MPEG demultiplexer61, video decoder 91, VR video encoder 92, audio decoder 81, VR audioencoder 82, VR multiplexer 62, and VR stream information detector 14.

The MPEG demultiplexer 61 splits the read MPEG data file into a videoelementary stream 601 and an audio elementary stream 602. The videodecoder 91 then decodes the video elementary stream 601 into decodedvideo data 901, and the VR video encoder 92 then converts and re-encodesthe decoded video data 901 to VR video stream 902.

The audio decoder 81 likewise decodes the audio elementary stream 602 toacquire decoded audio data 801, and the VR audio encoder 82 thenconverts and re-encodes the decoded audio data 801 to VR audio stream802.

The VR multiplexer 62 then multiplexes the VR video stream 902 and VRaudio stream 802 to a program stream compliant with the VR format, thatis, VR-compliant MPEG data 106.

The VR stream information detector 14 then acquires the managementinformation such as the stream VOBU (Video OBject Unit) informationrequired by the VR format from this VR-compliant MPEG data 106. The VRstream information detector 14 then generates and records VR-compliantVRO data file 107 and IFO data file 108 to optical disc 50.

The operation of this AV data converter is described next.

When the AV data converter reads MPEG data file 101, the MPEGdemultiplexer 61 demultiplexes the MPEG data file 101 into the videoelementary stream 601 and audio elementary stream 602. The videoelementary stream 601 is input to the video decoder 91 whereby it isdecoded and converted to decoded video data 901. The decoded video data901 is then passed to the VR video encoder 92, which converts it to a VRvideo elementary stream 902, that is, a video elementary stream definedby the VR format. The audio elementary stream 602 demultiplexed from theMPEG data file 101 by the MPEG demultiplexer 61 is similarly applied tothe audio decoder 81 whereby it is decoded and converted to decodedaudio data 801. This decoded audio data 801 is then converted by the VRaudio encoder 82 to a VR audio elementary stream 802, that is, an audioelementary stream defined by the VR format.

The VR multiplexer 62 then multiplexes the VR video elementary stream902 and VR audio elementary stream 802 to output VR-compliant MPEG data106 to the VR stream information detector 14. VRO data file 107 and IFOdata file 108 are then generated using the stream VOBU and othermanagement information detected by the VR stream information detector 14from the VR-compliant MPEG data 106.

A problem with this AV data converter of the prior art is that becauseall data in the read MPEG data file is decoded and all decoded data isthen encoded according to the VR format, conversion takes a long time.

Another problem is that the original image quality and sound quality maynot be retained in the converted AV data file depending upon theencoding conditions, and information is therefore lost.

Yet another problem is that because decoding and encoding are appliedeven when there is an error or other problem in the MPEG data file, anon-standard or corrupted data file that does not comply with the VRformat is created and a noncompliant disc is produced.

SUMMARY OF THE INVENTION

The present invention is directed to solving these problems, and anobject of the invention is to provide an AV data conversion apparatusand method capable of quickly converting AV data with little loss ofimage quality or sound quality, and preventing creation of noncompliantdiscs.

To achieve this object, an AV data conversion apparatus according to thepresent invention has a verification file confirmation means for readingan AV data file containing AV data including video information and audioinformation, and a verification file for the AV data file, andconfirming if the AV data file and verification file match; a pluralityof stream conversion means for changing the AV data to a specificformat; and a conversion method determining means for selecting fromamong the plural stream conversion means at least one stream conversionmeans for changing the AV data to the specific format based onverification file content.

A stream conversion method for converting an AV data file to a VR-formatAV data file can thus be easily selected by creating and appending tothe AV data file a verification file denoting the compatibility level ofthe AV data file with the VR format. This verification file can becreated and appended to the AV data file at the time the AV data file iscreated. The verification file confirmation means confirms thecorrelation between the AV data file and verification file, and thestream conversion method determining means evaluates AV data filecompatibility with the VR format based on the compatibility informationcontained in the verification file to select the appropriate streamconversion means.

The selected stream conversion means then re-encodes only the data thatis not compliant with the VR format. Because VR-compliant data is thusnot re-encoded, the conversion operation is fast with very little lossof image or sound quality.

Preferably, the AV data conversion apparatus reads a verification filecontaining AV data attributes from when the AV data file was created.The verification file confirmation means comprises an AV data attributeextraction means for extracting AV data attributes from the read AV datafile, and a comparison means for comparing the AV data attributesextracted by the AV data attribute extraction means with the AV dataattributes contained in the verification file. The stream conversionmeans converts the AV data to the specified format only when thecomparison means confirms an attribute match.

If the verification file confirmation means determines that the AV datafile does not conform to the verification file, stream conversion by thestream conversion means is prohibited and creating a disc that does notcomply to the standard is prevented at an early stage in the process.

Yet further preferably, the AV data conversion apparatus of thisinvention reads a verification file containing VenderID information foruniquely identifying a device or software that created the AV data file,and the stream conversion means determines at least one streamconversion means based on VenderID information.

By pre-registering in the stream conversion means which conversion meansis best for each VenderID, the best conversion means for a given AV datafile can be selected based on the VenderID information in theverification file. Compatibility of an AV data file with the VR formatdepends upon the device or software used to create the AV data file. Itis therefore desirable to set a VenderID for each device or softwareprogram, and correlate each VenderID to VR format compliance.

When the verification file confirmation means cannot read theverification file, the AV data conversion apparatus of this inventionfurther preferably creates a verification file containing AV dataattributes acquired by the AV data attribute extraction means andspecific VenderID information corresponding to the AV data attributes.

This aspect of the invention creates a new verification filecorresponding to the AV data attributes of the AV data file when theverification file cannot be read so that even AV data files for whichthere is no associated verification file can be converted.

A further aspect of the invention is an AV data conversion method havinga first step of reading an AV data file containing AV data includingvideo information and audio information, and a verification file for theAV data file; a second step of selecting at least one stream conversionmethod from among plural stream conversion methods for changing the AVdata to the specific format based on verification file content; and athird step of converting the AV data to a specific format by means ofthe at least one selected stream conversion method.

This method of the invention evaluates compliance with the VR formatbased on compatibility information contained in the verification file,and selects a stream conversion method appropriate to the compliancelevel indicated in the verification file. As a result, only data that isnot compliant with the VR format is re-encoded, and VR-compliant data isnot re-encoded. AV data files can therefore be converted quickly withlittle loss of video or sound quality.

Preferably, this AV data conversion method also has, after the firststep and before the second step, a fourth step of confirming if the AVdata file and verification file mutually correspond.

If the AV data file is determined to be a corrupt file not correspondingto the verification file, subsequent stream conversion is stopped andcreating a non-standard disc can be prevented at an early stage in theprocess.

Yet further preferably, this AV data conversion method reads averification file containing AV data attributes from when the AV datafile was created. In addition, the fourth step further comprises a fifthstep for extracting the AV data attributes when the AV data file wascreated from the read AV data file, and a sixth step for comparing theAV data attributes extracted by the fourth step with the AV dataattributes contained in the verification file. The third step convertsthe AV data to the specified format only when a comparison result fromthe sixth step confirms an attribute match.

Creating a non-standard disc can thus be prevented at an early stage inthe process because conversion by the stream conversion means isprohibited when the result of the fourth step is that the AV data fileis an illegal AV data file not conforming to the verification file.

Yet further preferably, this AV data conversion method reads averification file containing VenderID information uniquely identifying adevice or software that created the AV data file, and the second stepselects the conversion method based on this VenderID information.

By pre-registering in the stream conversion means which conversion meansis best for each VenderID, the best conversion method for a given AVdata file can be selected based on the VenderID information in theverification file.

An AV data conversion method according to another aspect of theinvention has a first step of reading an AV data file containing AV dataincluding video information and audio information; a second step ofextracting AV data attributes from the read AV data file; a third stepof creating a verification file corresponding to the extracted AV dataattributes; a fourth step of selecting at least one stream conversionmethod from among plural stream conversion methods for changing the AVdata to the specific format based on verification file content; and afifth step of converting the AV data to the specific format by applyingthe at least one selected stream conversion method.

This aspect of the invention creates a new verification filecorresponding to the AV data attributes of the AV data file when theverification file cannot be read so that even AV data files for whichthere is no associated verification file can be converted.

A further aspect of the invention is a computer-readable recordingmedium storing an AV data conversion program of this invention forexecuting on a computer the steps of the AV data conversion method. Therecording medium could be an optical recording medium, magneticrecording medium, semiconductor recording medium, or other typerecording medium.

An AV data conversion program according to the present invention is aprogram for executing on a computer the steps of an AV data conversionmethod according to this invention. This AV data conversion program canbe distributed on a recording medium or over the Internet or otherdigital communication medium.

It will thus be apparent that an AV data conversion apparatus accordingto the present invention decodes and encodes only data that iscompatible with the VR format based on a VenderID or other informationcontained in a verification file. As a result, the present invention canconvert AV data faster and with less loss of image quality or soundquality when compared with a conventional AV data conversion system thatdecodes and encodes all data.

Producing a non-compliant disc can also be prevented at an earlier stagein the process because information contained in the verification fileand information contained in the AV data file are compared, and datafile conversion is stopped if an error is detected in the AV data file.

Other objects and attainments together with a fuller understanding ofthe invention will become apparent and appreciated by referring to thefollowing description and claims taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become readily understood from the followingdescription of preferred embodiments thereof made with reference to theaccompanying drawings, in which like parts are designated by likereference numeral, and in which:

FIG. 1 is a block diagram of an AV data conversion apparatus accordingto a first embodiment of the present invention;

FIG. 2 is a block diagram showing an example of an AV data conversionapparatus according to a first embodiment of the invention;

FIG. 3 is a block diagram showing the configuration of the videocapturing means shown in FIG. 2;

FIG. 4 is a flow chart describing operation of the AV data conversionapparatus according to a first embodiment of the invention;

FIG. 5A is a schematic diagram of information contained in aVR-compatibility verification file;

FIG. 5B shows steps executed by the VR verification file confirmationmeans;

FIG. 6A is an example of a stream conversion means compatibility table;

FIG. 6B describes the stream conversion method determining means;

FIG. 7 is a block diagram describing operation of the 0-th streamconversion means 51;

FIG. 8 is a block diagram describing operation of the 1st streamconversion means 13 a;

FIG. 9 is a block diagram describing operation of the 2nd streamconversion means 13 b;

FIG. 10 is a block diagram describing operation of the 3rd streamconversion means 13 c;

FIG. 11 is a block diagram describing operation of the 4th streamconversion means 13 d;

FIG. 12 is a detailed block diagram of the loss-of-synchronizationdetection means and audio data correction means shown in FIG. 11;

FIG. 13 is a block diagram describing operation of the 5th streamconversion means 13 e;

FIG. 14 is a block diagram describing operation of the 6th streamconversion means 13 f;

FIG. 15 is a block diagram describing operation of the 7th streamconversion means 13 g;

FIG. 16 is a block diagram describing operation of the 8th streamconversion means 13 h;

FIG. 17 is a block diagram of an AV data conversion apparatus accordingto a second embodiment of the invention;

FIG. 18 is a flow chart of the operation of the AV data conversionapparatus according to the second embodiment of the invention; and

FIG. 19 is a block diagram of an AV data conversion apparatus accordingto the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described below withreference to the accompanying figures. Note that like reference numeralsin the figures denote identical components or components performingidentical actions and operations.

Embodiment 1

FIG. 1 is a block diagram of an AV data conversion apparatus accordingto a first embodiment of the present invention. As shown in FIG. 1, thisAV data conversion apparatus reads an MPEG data file 101 and aVR-compatibility verification file 102 corresponding to the MPEG datafile 101, and produces VR-format VRO file 107 and IFO file 108 through astream conversion operation. As will also be known from FIG. 1, this AVdata conversion apparatus has a VR-compatibility verification fileconfirmation means 11, stream conversion method determining means 12,stream conversion unit 13 containing at least one stream conversionmeans, and VR stream information detector 14.

The IFO file is a management information file containing informationrelating to the recorded MPEG stream. This information includes, forexample, the size and total number of GOP (data compression unit)objects, the size of each recorded data block, and the video signalresolution. The IFO file also contains the results of simple editingoperations based on the VR format.

The operation of each component of the AV data conversion apparatus isdescribed next.

The VR-compatibility verification file confirmation means 11 firstconfirms whether the MPEG data file 101 conforms to the VR-compatibilityverification file 102. The VR-compatibility verification file is pairedwith an MPEG data file and is used to verify the MPEG data file, andincludes MPEG data video attributes and audio attributes, andinformation about the compatibility of MPEG data contained in the MPEGdata file with the VR format.

If the VR-compatibility verification file confirmation means 11 verifiesthat the MPEG data file is compatible with the VR format (referred tobelow as “VR compliant”), the VR-compatibility verification fileconfirmation means 11 outputs the verified MPEG stream data 103 to thestream conversion unit 13, and outputs the MPEG verification data 104acquired from the VR-compatibility verification file 102 to the streamconversion method determining means 12.

Based on the MPEG verification data 104, the stream conversion methoddetermining means 12 determines the best stream conversion means of thestream conversion unit 13, and applies stream conversion meansidentifier 105 to the stream conversion unit 13.

In this embodiment of the invention the stream conversion unit 13includes first stream conversion means 13 a, second stream conversionmeans 13 b, and third conversion means 13 c, each performing a differentstream conversion function. Which of these stream conversion means isused to convert the MPEG data file is selected based on the streamconversion means identifier 105. The stream conversion unit 13 thenconverts the verified MPEG stream data 103 to VR-compliant MPEG streamdata 106, that is, an MPEG data stream that is compatible with the VRformat.

The VR stream information detector 14 then detects the stream VOBU andother management information required by the VR format from theVR-compliant MPEG data, and generates VR-compliant VRO file 107 and IFOfile 108.

The functions of the present invention shown in FIG. 1 can be renderedby a computer program executed by a personal computer, for example. FIG.2 is a block diagram showing the configuration of a personal computer 10for executing the method of the present invention by means of a CPU 1,memory 2, hard disk drive 3, DVD-RAM drive 4, and video capture device5. The CPU 1 reads and runs a computer program stored in memory 2 orhard disk drive 3. This computer program is typically distributed via arecording medium, but could be distributed via a digital communicationnetwork. The configuration of the video capture device 5 is describednext with reference to FIG. 3.

The video capture device 5 has an A/D converter 6, encoder 7, andVR-compatibility verification file generator 8. The A/D converter 6converts video input to the video capture device 5 to digital imagedata, and the encoder 7 then MPEG-encodes the digital image data tooutput MPEG data file 101. The VR-compatibility verification filegenerator 8 also generates VR-compatibility verification file 102containing information about the compatibility of the MPEG data file 101with the VR format. Compatibility with the VR format depends on thecharacteristics of the encoder 7. These characteristics differ accordingto the manufacturer and system design of the encoder 7. As a result,this embodiment of the invention adds a VenderID identifying the encoder7 manufacturer as the compatibility information in the VR-compatibilityverification file 102. It will be obvious to one with ordinary skill inthe related art that this VenderID shall not necessarily identify themanufacturer, and could instead be a unique ID determined by thecharacteristics of the encoder 7. The encoder 7 could further be eithera software or a hardware construction, and the VenderID predeterminedfor each encoder 7 or video capture device 5 can be added to theVR-compatibility verification file 102. The VenderID could also be addedaccording to the output MPEG data file 101.

The personal computer 10 acquires the MPEG data file 101 andVR-compatibility verification file 102 from the video capture device 5.The MPEG data file 101 is written to memory 2, and the program run bythe CPU 1 converts the MPEG stream data 103 contained in the MPEG datafile 101 to VR-compliant MPEG data 106 which is then written to DVD-RAMby the DVD-RAM drive 4, producing a VR-format optical disc 50. It shouldbe noted that the personal computer 10 of this embodiment has a videocapture device 5, but the video capture device 5 is not required as longas there is means for acquiring a MPEG data file 101 andVR-compatibility verification file 102 set. There could, for example, bea network connection enabling the AV data conversion method describedabove to be executed using an MPEG data file 101 and pairedVR-compatibility verification file 102 acquired from another device onthe network.

The present invention can also be rendered in a DVD recorder having theconstruction shown in FIG. 2 built in. In this case the program run bythe CPU 1 can be stored to memory 2 or hard disk drive 3. The memory 2could be ROM (read-only memory) or RAM (random access memory), and theprogram could be stored in a ROM device. This ROM device could be flashmemory, and the program recorded to flash memory can be overwritten witha program obtained from a communication network or recording medium.

The AV data conversion method of this invention is described step bystep next with reference to FIG. 4.

(a) The VR-compatibility verification file confirmation means 11 firstreads MPEG data file 101 and VR-compatibility verification file 102(S11).

(b) The VR-compatibility verification file confirmation means 11 thengets the MPEG verification information from the read VR-compatibilityverification file 102 (S12).

(c) Whether the MPEG data file 101 matches the VR-compatibilityverification file 102 is then verified based on the content of the MPEGverification information (S13).

(d) If the MPEG data file 101 and VR-compatibility verification file 102match, the stream conversion method determining means 12 selects thestream conversion unit 13 from the stream conversion meanscorrespondence table based on the VenderID contained in the MPEGverification information (S14). For example, if the VenderID isVender_C, second stream conversion means 13 b is selected by referencingthe table shown in FIG. 6A, and third conversion means 13 c is selectedif the VenderID is Vender_D. If the VenderID in the MPEG verificationinformation is not found in the stream conversion means correspondencetable, the process ends as shown in FIG. 6(b).

(e) The selected stream conversion unit 13 then applies the VRconversion process to the MPEG stream data 103 in the MPEG data file 101(S15).

(f) The VR stream information detector 14 then acquires the VOBU andother management information required by the VR format from theVR-compliant MPEG data 106, and generates the VR-compliant VRO file 107and IFO file 108 (S16).

The original MPEG data file 101 is thus output as VR-compliant MPEGstream data 106 as a result of these steps.

The AV data conversion method described above can also be executed as acomputer program.

Operation of an AV data conversion apparatus according to thisembodiment of the invention is described next with reference to the flowchart in FIG. 4.

The VR-compatibility verification file confirmation means 11 first readsthe MPEG data file 101 and VR-compatibility verification file 102 (S11).

Based on the content of the read VR-compatibility verification file 102,the VR-compatibility verification file confirmation means 11 thenverifies if the MPEG data file 101 corresponds to the VR-compatibilityverification file 102 (S12, S13).

The operation of the VR-compatibility verification file confirmationmeans 11 at this time is described in detail with reference to FIG. 5.As shown in FIG. 5A, the VR-compatibility verification file 102 iscomposed of, for example, MPEG file information denoting the file nameand file size, a VenderID denoting the type of system that produced theMPEG file, video attributes indicating the resolution and otherattributes of the video content, and audio attributes indicating suchinformation as the audio bitrate. Note that the file information, videoattributes, and audio attributes are collectively referred to as the AVdata attributes.

FIG. 5 (b) describes operation of the VR-compatibility verification fileconfirmation means 11. As shown in FIG. 5 (b) this VR-compatibilityverification file confirmation means 11 is composed of an MPEGinformation acquisition means 21, MPEG file information comparison means22, video attribute comparison means 23, and audio attribute comparisonmeans 24.

The MPEG information acquisition means 21 gets the file information,video attributes, and audio attributes from the AV data attributes ofthe MPEG data file. The MPEG file information comparison means 22 thendetermines if the filename, size, date, and other file attributes of theMPEG data file match the file information of the MPEG data file. Thevideo attribute comparison means 23 likewise determines if the videoresolution and other video attributes match, and the audio attributecomparison means 24 determines if the audio bitrate and other audioattributes match.

The VR-compatibility verification file 102 contains the MPEG fileinformation, VenderID, video attributes, and audio attributes atspecific locations in a known file format.

The MPEG information acquisition means 21 gets the MPEG fileinformation, video attributes, and audio attributes from the MPEG datafile. The MPEG file information comparison means 22 determines if theMPEG file information acquired from the MPEG data file matches the MPEGfile information of the VR-compatibility verification file, and stopsthe stream conversion process if a match is not confirmed. The videoattribute comparison means 23 determines if the video attributesacquired from the MPEG data file match the video attributes of theVR-compatibility verification file, and stops the stream conversionprocess if a match is not confirmed. The audio attribute comparisonmeans 24 likewise determines if the audio attributes from the MPEG datafile match the audio attributes of the VR-compatibility verificationfile (S13), and stops the stream conversion process if a match is notconfirmed. The stream conversion process thus continues and MPEGverification information storing the MPEG stream data and VenderID isoutput only if all information matches.

The MPEG verification information output from the VR-compatibilityverification file confirmation means 11 is input to the streamconversion method determining means 12. Operation of the streamconversion method determining means 12 is described next with referenceto FIGS. 6A and 6B.

FIG. 6A shows a sample stream conversion means correspondence table.This stream conversion means correspondence table records whichconversion process should be run for a particular VenderID in theVR-compatibility verification file. FIG. 6B describes the operation ofthe stream conversion method determining means 12.

The stream conversion method determining means 12 references the streamconversion means correspondence table 31, and the VenderID comparisonmeans 32 compares the VenderID in the VR-compatibility verification filewith the VenderIDs in the stream conversion means correspondence table31.

When the MPEG verification information is input to the stream conversionmethod determining means 12, the stream conversion means is selectedfrom the stream conversion means correspondence table based on theVenderID contained in the MPEG verification information (S14). Using thestream conversion means correspondence table shown in FIG. 6 by way ofexample, second stream conversion means 13 b is selected if the VenderIDis Vender_C, and third conversion means 13 c is selected if the VenderIDis Vender_D. Likewise, third stream conversion means 13 c and sixthstream conversion means 13 f are selected if the VenderID is Vender_E,fourth stream conversion means 13 d is selected if Vender_F, fifthstream conversion means 13 e is selected if Vender_G, sixth streamconversion means 13 f is selected if Vender-H, seventh stream conversionmeans 13 g if Vender_I, and eighth stream conversion means 13 h isselected if Vender_J. Processing stops as shown in FIG. 6 (b) if theVenderID contained in the MPEG verification information is not found inthe stream conversion means correspondence table.

The stream conversion method determining means 12 then inputs the streamconversion means selection to the stream conversion unit 13. Using theselected stream conversion means 13 a to 13 h, the stream conversionunit 13 applies the appropriate conversion process to the verified MPEGstream data 103 (S15).

Operation of the stream conversion unit 13 is described in detail nextwith reference to FIG. 7 to FIG. 16.

If stream conversion is unnecessary because the input verified MPEGstream data 103 is highly compliant with the VR format, the streamconversion unit 13 selects the 0-th stream conversion means 51. Thissituation corresponds to a VenderID of Vender_B in the table shown inFIG. 6A. The 0-th stream conversion means 51 then outputs the inputverified MPEG stream data 103 as VR-compliant MPEG stream data 106without further processing as shown in FIG. 7.

If the input verified MPEG stream data 103 is VR format compliant on thevideo and audio elementary stream level but not compatible on themultiplex level, the stream conversion unit 13 selects first streamconversion means 13 a (equivalent to a VenderID of Vender_A in FIG. 6).This first stream conversion means 13 a is described with reference toFIG. 8.

The first stream conversion means 13 a has an MPEG demultiplexer 61 andVR multiplexer 62. The MPEG demultiplexer 61 demultiplexes the verifiedMPEG stream data 103 into the video elementary stream 601 and audioelementary stream 602. The VR multiplexer 62 then combines the videoelementary stream 601 and audio elementary stream 602 to theVR-compliant MPEG stream data 106 of a VR program stream.

The MPEG demultiplexer 61 of the first stream conversion means 13 ademultiplexes the input verified MPEG stream data 103 into the videoelementary stream 601 and audio elementary stream 602. The VRmultiplexer 62 then converts these elementary streams to the VR formatby, for example, converting the pack size to 2048 bytes, and thusoutputs VR-compliant MPEG stream data 106.

It will thus be apparent from FIG. 8 that when the input verified MPEGstream data 103 is compatible with the VR format on the video and audioelementary stream level, the first stream conversion means 13 a convertsthe verified MPEG stream data 103 to VR-compliant MPEG stream data 106by simply multiplexing the elementary streams without decoding orencoding the streams.

If the input verified MPEG stream data 103 is compatible with the VRformat on the video and audio elementary stream level except for someselected flags, the stream conversion unit 13 selects second streamconversion means 13 b (equivalent to a VenderID of Vender_C in FIG. 6).Operation of the second stream conversion means 13 b is described nextwith reference to FIG. 9.

As shown in FIG. 9, the second stream conversion means 13 b is composedof MPEG demultiplexer 61, VR multiplexer 62, video stream correctionmeans 71, and audio stream correction means 72. The video streamcorrection means 71 corrects the video elementary stream 601 so that itis compatible with the VR format on the video elementary stream level,and thus outputs corrected video elementary stream 701. The audio streamcorrection means 72 corrects the audio elementary stream 602 so that itis compatible with the VR format on the audio elementary stream level,and thus outputs corrected audio elementary stream 702.

The second stream conversion means 13 b thus splits the input verifiedMPEG stream data 103 into video elementary stream 601 and audioelementary stream 602 by means of MPEG demultiplexer 61. The videostream correction means 71 then changes or deletes particular flags inthe video elementary stream 601 according to the VR format, and theaudio stream correction means 72 likewise changes or deletes particularflags in the audio elementary stream 602 according to the VR format. TheVR multiplexer 62 then converts the MPEG-2 program stream conforming tothe VR format to 2048-byte packs, for example, and outputs VR-compliantMPEG stream data 106.

The second stream conversion means 13 b runs a conversion process forcases in which the values of only some flags in the video and audio ofthe input MPEG data file are incompatible with the VR format. If onlythe display resolution of the MPEG data is not compatible with the VRformat, for example, the MPEG data can be converted to VR-format streamdata by changing only the data relating to the display resolutioncontained in the video elementary stream isolated by the demultiplexer,and full decoding and encoding are therefore not necessary.

If the input verified MPEG stream data 103 is VR-compliant on the videoelementary stream level, the stream conversion unit 13 selects the thirdstream conversion means 13 c (corresponding to a VenderID of Vender_D inFIG. 6). Operation of the third stream conversion means 13 c isdescribed with reference to FIG. 10.

As shown in FIG. 10 the third stream conversion means 13 c has a MPEGdemultiplexer 61, VR multiplexer 62, audio decoder 81, and VR audioencoder 82. The audio decoder 81 decodes the audio elementary stream 602and outputs decoded audio data 801. The VR audio encoder 82 then encodesthe decoded audio data 801 to VR-format VR audio elementary stream 802.

The input verified MPEG stream data 103 is demultiplexed by the MPEGdemultiplexer 61 of the third stream conversion means 13 c to videoelementary stream 601 and audio elementary stream 602. The audioelementary stream 602 is then decoded by the audio decoder 81. Thedecoded audio data 801 is then encoded by the VR audio encoder 82 to aVR audio elementary stream 802 as defined by the VR format. The VRmultiplexer 62 then converts the VR-compliant MPEG-2 program stream to2048-byte packs, for example, and outputs VR-compliant MPEG stream data106.

If only the audio portion of the input MPEG data file 101 isincompatible with the VR format, a VR-compliant MPEG stream data 106 canbe output by re-encoding only the audio portion instead of re-encodingall data.

If the input verified MPEG stream data 103 is VR compliant at the videoelementary stream level but AV synchronization is off, the streamconversion unit 13 selects the fourth stream conversion means 13 d(equivalent to a VenderID of Vender_F in FIG. 6A). Operation of thefourth stream conversion means 13 d is described next with reference toFIG. 11.

As shown in FIG. 11 the fourth stream conversion means 13 d has MPEGdemultiplexer 61, VR multiplexer 62, audio decoder 81, VR audio encoder82, loss-of-synchronization detector 83, and audio data correction means84. The loss-of-synchronization detector 83 compares video timeinformation 803 and audio time information 806 to detect any offset inthe video and audio playback times, and outputs audio correctioninformation 804 denoting how much to correct the audio data. The audiodata correction means 84 then adjusts the data size of the decoded audiodata 801 according to the correction specified by the audio correctioninformation 804, and outputs AV-synchronization-corrected audio data805. The audio component of the AV-synchronization-corrected audio data805 is corrected to resynchronize the video and audio.

The MPEG demultiplexer 61 of the fourth stream conversion means 13 ddemultiplexes the input verified MPEG stream data 103 into the videoelementary stream 601 and audio elementary stream 602, and outputs AVsynchronization data 803, 806 containing a Presentation Time Stamp(PTS), that is, time information for synchronizing video and audioplayback. Based on the AV synchronization data 803, 806, theloss-of-synchronization detector 83 detects any offset between the videoand audio, and outputs audio correction information 804. Based on thisaudio correction information 804, the audio data correction means 84adjusts the data size of the decoded audio data 801, and outputsAV-synchronization-corrected audio data 805, that is, the audio dataafter correcting it to synchronize with the video. ThisAV-synchronization-corrected audio data 805 is then encoded by the VRaudio encoder 82 to a VR audio elementary stream 802. The VR multiplexer62 then multiplexes the data according to the VR format and outputsVR-compliant MPEG stream data 106.

When re-encoding the audio part of input MPEG data file 101 could causea loss of synchronization between the video and audio, the MPEG datafile 101 can be converted to synchronized VR-format data by increasingor decreasing the audio data according to the video data.

This synchronization correction method is described in further detailwith reference to FIG. 12. FIG. 12 is a detailed block diagram of theloss-of-synchronization detector 83 and audio data correction means 84.

(1) The MPEG demultiplexer 61 demultiplexes the input verified MPEGstream data 103 into the video elementary stream 601 and audioelementary stream 602. The MPEG demultiplexer 61 also outputs AVsynchronization information 803 containing the PTS or other timeinformation enabling synchronized playback of the video and audio.

(2) The loss-of-synchronization detector 83 then acquires the totalvideo frame count (time equivalent) as the AV synchronizationinformation 803 (S01).

(3) The average difference between the video and audio is thencalculated for a predetermined period. The offset between this averageand the difference between the video and audio is then calculated (S02).This step is necessary because the average difference calculated in thefirst predetermined period will vary according to the currentenvironment.

(4) Whether this difference exceeds a specified threshold value is thendetermined (S03). If the difference exceeds the threshold value, theaudio correction information 804 is sent to the audio data correctionmeans 84.

(5) The audio data correction means 84 acquires the decoded audio data801 a and audio data size (time-equivalent) 806 from the audio decoder81 (S04).

(6) The loss-of-synchronization detector 83 acquires the audiocorrection information 804 from the loss-of-synchronization detector,and calculates the required audio data correction (S05).

(7) If the audio data correction required for decoded audio data 801 bis a non-zero value, the audio data size is increased or decreasedaccordingly (S06). Adjusting the audio data at once can cause the audioto skip or sound unnatural after conversion is completed, and a gradualadjustment in the audio data size is therefore desirable. The data isdownsampled at specified intervals in order to reduce the amount ofdata, and data is duplicated at specified intervals to graduallyincrease the amount of audio data. This operation continues until thespecified desired audio data correction is achieved.

Note that this synchronization correction method is described in furtherdetail in International Application PCT/JP02/05108 (WO 02/097817),incorporated herein by reference.

(8) AV-synchronization-corrected audio data 805 corrected to synchronizewith the video stream is output to the VR audio encoder 82.

(9) The VR audio encoder 82 then encodes theAV-synchronization-corrected audio data 805 to a VR audio elementarystream 802.

(10) The VR multiplexer 62 then converts the video elementary stream 601and VR audio elementary stream 802 to conform to the VR format, therebyoutputting VR-compliant MPEG stream data 106.

If the verified MPEG stream data 103 is VR-compliant at the audioelementary stream level but not at the video elementary stream level,the stream conversion unit 13 selects the fifth stream conversion means13 e (equivalent to a VenderID of Vender_G in the correspondence tableshown in FIG. 6A). This fifth stream conversion means 13 e is describednext with reference to FIG. 13.

As shown in FIG. 13 the fifth stream conversion means 13 e is composedof a MPEG demultiplexer 61, VR multiplexer 62, video decoder 91, and VRvideo encoder 92. The video decoder 91 decodes the video elementarystream 601 and outputs decoded video data 901. The VR video encoder 92encodes the decoded video data 901 and outputs VR video elementarystream 902.

The MPEG demultiplexer 61 of fifth stream conversion means 13 edemultiplexes the input verified MPEG stream data 103 to videoelementary stream 601 and audio elementary stream 602. The video decoder91 then decodes the video elementary stream 601. The VR video encoder 92then encodes the decoded video data 901 to a VR video elementary stream902. The VR multiplexer 62 then converts the VR video elementary stream902 according to the VR format, and outputs VR-compliant MPEG streamdata 106.

An MPEG data file in which only the video component is not compliantwith the VR format can thus be converted to a VR-compliant AV datastream by re-encoding only the video portion rather than re-encoding alldata.

If the input verified MPEG stream data 103 is compatible with the VRformat at the audio elementary stream level but audio synchronization islot, the stream conversion unit 13 selects the sixth stream conversionmeans 13 f (corresponding to a VenderID of Vender_H in thecorrespondence table shown in FIG. 6A). This sixth stream conversionmeans 13 f is described below with reference to FIG. 14.

As shown in FIG. 14, the sixth stream conversion means 13 f is composedof a MPEG demultiplexer 61, VR multiplexer 62, video decoder 91, VRvideo encoder 92, loss-of-synchronization detector 93, and video datacorrection means 94.

The loss-of-synchronization detector 93 compares the audio timeinformation 903 and video time information 906 to detect the differencebetween the video and audio playback times, and outputs video datacorrection information 904 denoting the required video data correction.The video data correction means 94 then adjusts the video data sizeaccording to the video correction indicated by the video data correctioninformation 904, and outputs AV-synchronization-corrected video data905. The video data of the AV-synchronization-corrected video data 905is adjusted to synchronize the video with the audio. It should be notedthat the detailed operation of the loss-of-synchronization detector 93and video data correction means 94 is the same as the operation of theaudio data correction means, and further description thereof is thusomitted.

The MPEG demultiplexer 61 of the sixth stream conversion means 13 fdemultiplexes the verified MPEG stream data 103 into the videoelementary stream 601 and audio elementary stream 602, and outputs AVsynchronization information 903, 906 including a PTS or other timeinformation enabling synchronized playback of the video and audio.

The loss-of-synchronization detector 93 detects a loss ofsynchronization between the video and audio based on the AVsynchronization information 903, 906, and outputs video data correctioninformation 904. Based on this video data correction information 904,the video data correction means 94 adjusts the size of the decoded videodata 901, and outputs AV-synchronization-corrected video data 905, whichhas been corrected for synchronization with the audio. ThisAV-synchronization-corrected video data 905 is encoded by the VR videoencoder 92 to a VR video elementary stream 902. The VR multiplexer 62then converts the video and audio to output VR-compliant MPEG streamdata 106.

This method of the invention can thus convert an input MPEG data file toa VR-compliant data file free of synchronization errors by adjusting thevideo data size to the audio data when synchronization between the videoand audio can be lost by re-encoding the video portion of an input MPEGdata file.

When both the video elementary stream and audio elementary stream of theinput verified MPEG stream data 103 are incompatible with the VR format,the stream conversion unit 13 selects seventh stream conversion means 13g (corresponding to a VenderID of Vender_I in the correspondence tableshown in FIG. 6A). This seventh stream conversion means 13 g isdescribed further with reference to FIG. 15.

The seventh stream conversion means 13 g is composed of MPEGdemultiplexer 61, VR multiplexer 62, audio decoder 81, VR audio encoder82, video decoder 91, and VR video encoder 92.

The audio decoder 81 decodes the audio elementary stream 602 and outputsdecoded audio data 801. The VR audio encoder 82 encodes the decodedaudio data 801 and outputs VR audio elementary stream 802. The videodecoder 91 decodes video elementary stream 601 and outputs decoded videodata 901. The VR video encoder 92 encodes decoded video data 901 andoutputs VR video elementary stream 902.

The MPEG demultiplexer 61 of seventh stream conversion means 13 gdemultiplexes the input verified MPEG stream data 103 to videoelementary stream 601 and audio elementary stream 602. The video decoder91 then decodes the video elementary stream 601, and the audio decoder81 decodes the audio elementary stream 602. The decoded video data 901is encoded to a VR video elementary stream 902 by the VR video encoder92, and the decoded audio data 801 is encoded to a VR audio elementarystream 802 by the VR audio encoder 82. The VR multiplexer 62 thenconverts these elementary streams to the VR format, and outputsVR-compliant MPEG stream data 106.

If neither the video nor the audio portion of the input MPEG data file101 is compatible with the VR format, the MPEG data file 101 can thus beconverted to VR-format data by re-encoding both the video and audioportions.

If the input verified MPEG stream data 103 is not compatible with the VRformat on either the video or audio elementary stream level, and a lossof synchronization is also detected in the AV data, the streamconversion unit 13 selects the eighth stream conversion means 13 h(equivalent to a VenderID of Vender_J in the correspondence table shownin FIG. 6A). This eighth stream conversion means 13 h is described nextwith reference to FIG. 16.

The MPEG demultiplexer 61 of this eighth stream conversion means 13 hdemultiplexes the input verified MPEG stream data 103 to videoelementary stream 601 and audio elementary stream 602, and outputs AVsynchronization information 803 including the PTS enabling synchronousaudio and video playback.

Based on the AV synchronization data 803, the loss-of-synchronizationdetector 83 detects a difference between the audio and video playbacktimes, and outputs audio correction information 804. Based on the audiocorrection information 804, the audio data correction means 84 adjuststhe decoded audio data 801 and outputs AV-synchronization-correctedaudio data 805, that is, the decoded audio data 801 corrected for videosynchronization. The VR audio encoder 82 then encodes thisAV-synchronization-corrected audio data 805 to a VR audio elementarystream 802.

The video elementary stream 601 is likewise decoded by the video decoder91. The decoded video data 901 is then encoded by the VR video encoder92 to a VR video elementary stream 902. The VR video elementary stream902 is then converted to a VR video stream, and VR-compliant MPEG streamdata 106 is output.

When neither the video nor audio portions of the input MPEG data file101 is compatible with the VR format and the video and audio may go outof synchronization, VR-format data with no loss of synchronization canbe output by re-encoding the video and audio, and then adjusting theaudio to the video data size.

The stream conversion unit 13 thus selects one of the stream conversionmeans 0 to 8, and converts the input MPEG data stream using the selectedstream conversion means. The VR stream information detector 14 then getsthe VOBU and other management information required by the VR format fromthe VR-compliant MPEG stream data 106. A VR-compliant VRO file and IFOfile are then created (S16).

It should be noted that the stream conversion means is determined basedon the VenderID information by the stream conversion method determiningmeans 12 in the embodiment described above, but the stream conversionmeans could be determined based on AV data attributes such as the MPEGfile information, video information, and audio information. In this casea correspondence table relating the AV data attributes and streamconversion means can be used instead of the stream conversion meanscorrespondence table shown in FIG. 6A.

Compatibility between the MPEG data file 101 and VR format is describednext. MPEG files can be encoded according to various specifications. AnMPEG data file 101 that is VR compliant is therefore described below.

The video elementary stream of an MPEG title is compatible with the VRformat only for NTSC (PAL) resolutions of 720×480 (720×576), 704×480(760×576), 352×480 (352×576), 352×240 (352×288), 544×480 (544×576), and480×480 (480×576). The video elementary stream is also compatible withthe VR format only when the video bitrate is 9.8 Mbps or less (MPEG-2),or 1.856 Mbps or less (MPEG-1).

The audio elementary stream is compatible with the VR format only if theaudio compression method is AC3, MPEG-1, MPEG-2, or LPCM; the samplingfrequency is 48 kHz; the channel is channel 1 (1 ch) through 8 (8 ch);and the bitrate is 64 Kbps/80 Kbps/96 Kbps/112 Kbps/128 Kbps/10 Kbps/192Kbps/224 Kbps/256 Kbps/320 Kbps/384 Kbps/448 Kbps/748 Kbps (LPCM)/1536Kbps (LPCM).

Compatibility with VR format multiplexing is described next. Theconditions for VR compatibility are that the pack size is fixed at 2048bytes and the playback time from one system header to the next systemheader (VOBU) is at least 0.4 second and 1 second or less. All video andaudio data must be completely contained in one VOBU, and the bitratemust be 10.08 Mbps or less for VR format compliance.

Embodiment 2

An AV data conversion apparatus according to a second embodiment of theinvention is described next. The first embodiment described aboveassumes the existence of a VR-compatibility verification file for theMPEG data file being processed. This second embodiment of the inventionapplies to a process used when a VR-compatibility verification filecorresponding to the MPEG data file 101 does not exist.

FIG. 17 is a block diagram showing the configuration of an AV dataconversion apparatus according to a second embodiment of the invention.Like parts are identified by like reference numerals in FIG. 1 and FIG.17, and further description thereof is thus omitted here. FIG. 18 is aflow chart showing the operation of this second embodiment. Stepsidentified by the same reference numeral in FIG. 4 and FIG. 18 performthe same operation, and further description thereof is this omittedhere.

As shown in FIG. 17 this AV data conversion apparatus has an MPEGinformation acquisition means 21, a virtual VR-compatibilityverification file generator 41, and a VR-compatibility file confirmationmeans 42. The MPEG information acquisition means 21 acquires fileinformation and video and audio attribute data from the MPEG data file.The virtual VR-compatibility verification file generator 41 then createsa VR format verification file based on the attributes acquired by theMPEG information acquisition means 21.

The operation of an AV data conversion apparatus according to thissecond embodiment of the invention is described below with reference tothe flow chart shown in FIG. 18.

The VR-compatibility file confirmation means 42 first reads the MPEGdata file and corresponding VR-compatibility verification file. If theVR-compatibility verification file is found, operation is the same asdescribed in the first embodiment (S22, S23, S13 to S16), and furtherdescription thereof is thus omitted. If the VR-compatibilityverification file cannot be read because there is no VR-compatibilityverification file corresponding to the MPEG data file 101, for example,the MPEG information acquisition means 21 gets the AV data attributesincluding video attributes such as the file size, file creation date,the video resolution, and other video file information, and audioattributes such as the audio bitrate.

In addition to the file information, video information, and audioattributes acquired by the MPEG information acquisition means 21, thevirtual VR-compatibility verification file generator 41 adds a virtualVenderID to these AV data attributes, and creates a VR-compatibilityverification file such as shown in FIG. 5 (S25). The virtual VenderIDassigned here is a reserved VenderID such as Vender_X.

The stream conversion method determining means 12 then selects streamconversion means X as the stream conversion means corresponding toVender_X (S14). This stream conversion means X corresponds to seventhstream conversion means 13 g or eighth stream conversion means 13 hdescribed in the first embodiment above, and encodes both the video andaudio (S15).

The stream conversion unit 13 then applies stream conversion asdescribed in the first embodiment, and the VR stream informationdetector 14 creates the VRO file and IFO file output as a VR format file(S16).

It is therefore possible to convert an MPEG data file to a VR formatfile by creating a virtual VR-compatibility verification file when onlya MPEG data file is present.

The present invention can also be rendered as a computer program. Thisprogram can also be distributed via an electrical communications mediumor recording medium so that the invention can be rendered using acomputer.

Although the present invention has been described in connection with thepreferred embodiments thereof with reference to the accompanyingdrawings, it is to be noted that various changes and modifications willbe apparent to those skilled in the art. Such changes and modificationsare to be understood as included within the scope of the presentinvention as defined by the appended claims, unless they departtherefrom.

1. An AV data conversion apparatus comprising: a verification fileconfirmation means for reading an AV data file containing AV dataincluding video information and audio information, and a verificationfile for the AV data file, and confirming if the AV data file andverification file mutually correspond; a plurality of stream conversionmeans for changing the AV data to a specific format; and a conversionmethod determining means for selecting from among the plural streamconversion means at least one stream conversion means for changing theAV data to the specific format based on verification file content.
 2. AnAV data conversion apparatus according to claim 1, wherein theverification file contains AV data attributes from when the AV data filewas created; wherein the verification file confirmation means comprises:an AV data attribute extraction means for extracting AV data attributesfrom the read AV data file; and a comparison means for comparing the AVdata attributes extracted by the AV data attribute extraction means withthe AV data attributes contained in the verification file; and whereinthe stream conversion means converts the AV data to the specified formatonly when the comparison means confirms an attribute match.
 3. An AVdata conversion apparatus according to claim 1, wherein the verificationfile contains VenderID information for uniquely identifying a device orsoftware that created the AV data file; and the stream conversion meansdetermines at least one stream conversion means based on VenderIDinformation.
 4. An AV data conversion apparatus according to claim 2,wherein the verification file confirmation means further comprises averification file creation means for creating a verification filecontaining AV data attributes acquired by the AV data attributeextraction means and specific VenderID information corresponding to theAV data attributes when a verification file corresponding to the AV datafile cannot be read.
 5. An AV data conversion method comprising: a firststep of reading an AV data file containing AV data including videoinformation and audio information, and a verification file for the AVdata file; a second step of selecting at least one stream conversionmethod from among plural stream conversion methods for changing the AVdata to the specific format based on verification file content; and athird step of converting the AV data to a specific format by means ofthe at least one selected stream conversion method.
 6. An AV dataconversion method according to claim 5, further comprising, after thefirst step and before the second step, a fourth step of confirming ifthe AV data file and verification file mutually correspond.
 7. An AVdata conversion method according to claim 6, wherein the verificationfile contains AV data attributes from when the AV data file was created;wherein the fourth step further comprises: a fifth step for extractingAV data attributes from the read AV data file, and a sixth step forcomparing the AV data attributes extracted with the AV data attributescontained in the verification file; and wherein the third step convertsthe AV data to the specified format only when a comparison result fromthe sixth step confirms an attribute match.
 8. An AV data conversionmethod according to claim 5, wherein the verification file containsVenderID information for uniquely identifying a device or software thatcreated the AV data file; and the second step selects the conversionmethod based on VenderID information.
 9. An AV data conversion methodcomprising: a first step of reading an AV data file containing AV dataincluding video information and audio information; a second step ofextracting AV data attributes from the read AV data file; a third stepof creating a verification file corresponding to the extracted AV dataattributes; a fourth step of selecting at least one stream conversionmethod from among plural stream conversion methods for changing the AVdata to the specific format based on verification file content; and afifth step of converting the AV data to the specific format by applyingthe at least one selected stream conversion method.
 10. An AV dataconversion method according to claim 9, wherein the verification filecontains specific VenderID information corresponding to the extracted AVdata attributes; and the fourth step selects the conversion method basedon the VenderID information.
 11. A computer-readable recording mediumstoring a program for executing on a computer the steps of an AV dataconversion method comprising a first step of reading an AV data filecontaining AV data including video information and audio information,and a verification file for the AV data file; a second step of selectingat least one stream conversion method from among plural streamconversion methods for changing the AV data to the specific format basedon verification file content; and a third step of converting the AV datato a specific format by means of the at least one selected streamconversion method.
 12. An AV data conversion program for executing on acomputer the steps of an AV data conversion method comprising: a firststep of reading an AV data file containing AV data including videoinformation and audio information, and a verification file for the AVdata file; a second step of selecting at least one stream conversionmethod from among plural stream conversion methods for changing the AVdata to the specific format based on verification file content; and athird step of converting the AV data to a specific format by means ofthe at least one selected stream conversion method.
 13. An AV dataconversion apparatus according to claim 2, wherein the verification filecontains VenderID information for uniquely identifying a device orsoftware that created the AV data file; and the stream conversion meansdetermines at least one stream conversion means based on VenderIDinformation.
 14. An AV data conversion method according to claim 6,wherein the verification file contains VenderID information for uniquelyidentifying a device or software that created the AV data file; and thesecond step selects the conversion method based on VenderID information.15. An AV data conversion method according to claim 7, wherein theverification file contains VenderID information for uniquely identifyinga device or software that created the AV data file; and the second stepselects the conversion method based on VenderID information.